Crystallization apparatus



July 31, 1928. 1,679,055

v w. SEIDEL v CRYSTALLIZATION APPARATUS Filed May 16. 1927 Patented Jul31, 1928.

1,619,055 .,UNITED STATES PATENT OFFICE.

'WALTER SEIDEL, OF LEVERKUSEN, GERMANY, ASSIGNOB TO I. G.FARBENINDUS'I'BII AKTIENGESELISCHAIFT, OF FRANKFORT-ON-EEHE-MAIN,GERMANY.

'CRYSTALLIZATIQN AIEIPARATUS. I

Application filed m 16, 1927, Serial No. 191,860, and in Germany Junea9, 1026.

The present invention relates to an improved form of crystallizationapparatus. ..With the crystallization apparatus and processes availableat present it is difiicult to produce crystals of large size if thecrystals formed have arela'tively high specific gravity compared to themother liquor and consequently tend to settle into a compact mass at thebottom of the crystallizing vessel. Under present practice it has beenfound to be fairly easy to produce large crystals of substances such assugar, potassium ferrocyanide,'sodium thiosulfate, and the like, whichmay be maintained in suspension in the mother liquor with littledifficult but these same methods are impracticable or the production oflarge crystals of substances such as potassium bichromate and bariumchloride and the like which are of relatively high specific gravitycompared; to these mother liquors. v

The principal object ofth'e present invention is the provision of a'ri'aparatus capable of producing large crystals rom solutions of substanceswhich form crystals of relatively highspecific ravity. The invention is,however, .not lim ted to the production of crystals of this character,and may be advantageously applied to the production of all kinds ofcrystals. A

The preferred form of apparatus embodyingmy invention-is shown in theaccompanyvinodrawings, 0f which:

talli zing vessel and of means for imparting a rocking motion thereto;

Fig. 2 is a perspective view of the crystallizing vessel; 4

Fig. 3 is a cross-sectional view of the crystallizing vessel;

Fig. .4 is a similar view illustrating the' I operation of the device inthe extreme tilted or rocked position; and

Fig. 5 is a cross-sectional view of a modified form of the crystallizingvessel.

The crystallizing vessel illustrated in Figs. 2, 3 and 4 is generallytrough shapedand may be of any suitable length and comprises the endwalls 1. 1, outwardly curved s1de walls 2, 2, and the upwardly archedbottom 3, these elements defining a central longitudinally extendingridge 4 dividing the vessel into the two lateral longitudinallyextending chambers 5, 5. As is evident the crystallizing vessel may beconstructed of ig. -1 is,a vertical end view-of the crystom 3 and sidewalls 2, 2, being made of a single suitably shaped piece of material asshown, these parts may bebuilt up, for instance, of wood. It is notedmoreover that the s de walls 2, 2, need not be of the substantiallysemi-circular cross-sectional shape lllustrated and that the ridge 4 maybe provided otherwise than by arching the bottom 3 and may vary in shapeand height wlthout departure from my invention. In operation thecrystallizing vessel is rocked from side to side,-cradlewise, preferablyon an axis lying in a vertical plane passing through the peak of theridge 4 and in or near to the peak of the ridge 4.

u A suitable apparatus for imparting a rockmg movement to thecrystallization vessel is shown in, Fig. 1. The apparatus comprisessupporting rods 6 pivotally secured to the crystallization vesseland tocross-arms 7 whlch are fixedly secured to the revoluble axle 8 mountedon support 15. 'Axle- 8 is provlded'with' an arm 9 which is connected bya 'pivoted link 10 to a cam device for imparting an oscillating movementthereto. The cam device shown consists of a rotatable shaft 13, a cam 12secured to said shaft, and a shell 11 enclosing cam 12 and attached tolink 10. .By rotation of shaft "13 a reciprocating movement of link 10is produced which in turn acting through arm 9 and axle 8 produces arocking movement of crossarms 7 and the crystallization vessel suspendedtherefrom by rods 6.' The particular means shown for producing. arockingmove ment of thecrystallization vessel forms no vices may be substitutedfor it for this purpose without departing from my invention. Themodification of the crystallizing vessel illustrated in Fig. 5 differsfrom the crystallizing vessel of Figs. 1, 2 and 3 only in that thebottom 3 is provided with a plurality of ridges 4 defining the chambers5. 5, and intermediate chambers 5.

The principle involved in the construction of the apparatus and in itsoperation is that as the crystallizing vessel is rocked from side toside the mother liquor flows from side to side carrying small crystalswhich have been formed in suspension while the larger crystals remain inthe chambers 5, -5. At each rocking of the vessel, the crystals in thehigher chamber 5 are drained while the rush of mother liquor from thehigher chamber 5 into the lower chamber 5- agitates the deposit ofcrystals therein and brings about an intimate contact between thecrystals and the mother liquor. As will be apparent the continuous orrepeated rocking of the vessel from side to side will alternately drainthe mother liquor from the deposit of crystals in one of the chambers5'and agitate and mix it with the deposit of crystals in the otherchamber 5. The side walls 2, 2, of the vessel are shaped to prevent themother liquor from spilling out while the bottom 3 is so shaped as tohold the deposited crystals in the chambers 5, 5, while permittingsubstantially all of the mother liquor to drain from side to side as thevessel is rocked from side to side. With this understanding oftheprinciples involved it will be apparent that the helght and shape of theridge 4 may vary considerably. The shape and relative height illustratedhas been found to give excellent resalts with a variety of solutions.One point to be considered in shaping the ridge 4 is the agitation ofthe deposits of crystals in the chambers 5, 5, by the flow of the motherliquor. Fig. 3 shows the crystallizing vessel in horizontal positionwith a deposit of crystals in each of the chambers 5, 5, and the levelof the mother liquor while Fig. 4 shows the crystallizing vessel intilted position with the crystalsin the upper chamber completelydrained. The operation of the apparatus illustrated in Fig. 5 is thesame as that of the apparatus illustrated in Figs. 2, 3 and 4 exceptingthat each ofthe chambers 5' also holds a deposit of crystals and each ofthe end chambers 5, 5, must be sufliciently large to hold all of themother liquor.

The process may be carried out upon batches ofsolution. but preferablyis applied to a continuous flow, the crystallizing vessel being suitablyinclined from end to end and the crystallizing solution being suppliedat one end and discharged at the other end when its supersaturation isexhausted. The crystals deposited in the chambers 5,, 5, will show atendency to move toward the lower chambers, comprises end of thecrystallizing vessel with the solu- The above apparatus has been foundto be especially well adapted to the production of crystals of potassiumbichromate and barium chloride.

I claim: 1. Crystallization apparatus, comprising a vessel adapted tohave a rocking movement imparted thereto, means dividing said vesselinto two lateral chambers, said means being disposed so as to permitdrainage of sub-- stantially all the liquid from the higher chamber tothe lower chamber in each extreme rocked position of the vessel and to'prevent the movement of the bulk of the crystals from one chambcrto theother.

2. Apparatus as in claim .1, wherein the means for dividing the vesselinto two lateral chambers, comprises a ridge-like member disposed alongthe bottom of said vessel.

3. Apparatus as in claim 1, wherein the means for dividing the vesselinto two lateral an inwardly arched portion forming an integral part ofthe bottom of said vessel.

4. Crystallization apparatus, comprisinga rectangularly shaped vessel ofrelatively great length adapted to have a rocking motion impartedthereto, a ridge-like longitudinal member dividing said vessel into twO.lateral chambers, said ridge-like member being disposed so as to permitdrainage of substantially all the liquid from the higher chamber to thelower chamber in each e;-

-treme rocked position of the vessel and to prevent the movement of thebulk of the crystals from one chamber to the other.

In testimony whereof,I affix my signa-.

ture.

WALTER SEIDEL.

